Okara treated with high hydrostatic pressure assisted by Ultraflo® L: Effect on solubility of dietary fibre

Okara is an abundant and inexpensive by-product from soybean, rich in total dietary fibre (> 55% dry weight), but poor in soluble dietary fibre (SDF, < 5% dw). A combined method of high hydrostatic pressure (HHP) aided by the food grade enzyme Ultraflo® L was used for SDF maximization. At atmospheric pressure, incubation time was not a key factor, and a ratio of 1:40 (enzyme:Okara, v/w) was able to saturate the enzyme within 120–150 min. When HHP plus Ultraflo® L were applied, a synergy between both treatments was observed. Thus, at 600 MPa, 0.025% Ultraflo® L and 30 min treatment, soluble carbohydrate added up to 15.64 ± 0.32%, consisting of two peaks (9.14 ± 0.18 and 0.57 ± 0.01 kDa), determined by HPLC-ELSD. The combination of HHP plus Ultraflo® L on Okara improved the solubility of the dietary fibre, making it more suitable to be used in functional foods.Industrial relevanceThere is an increasing interest in finding new prebiotics from food industrial waste. Okara has been simultaneously treated with Ultraflo® L and HHP, taking into account the industrial costs of the procedure, and adjusting the quantity of enzyme and time of treatment to the minimum, by a Response Surface Methodology and an enzymatic activity assay. Besides, an HPLC-ELSD direct analysis (High Performance Liquid Chromatography with Evaporative Light Scattering Detector) was employed to monitor soluble fibre, as an easy and fast analytical method.     

Field study on the microbiological quality of pickles in brine and survival of Salmonella Typhimurium and Listeria monocytogenes during storage at 4 °C

The aim of this study was to assess the microbiological quality and the ability of Listeria monocytogenes and Salmonella enterica serovar Typhimurium strains to survive during storage at 4 °C of all available brand names of brined pickles and some in-bulk ones, in the district of Athens. None of the samples could be characterized as heavily contaminated. The microbial populations detected could be due to inadequacy of packaging, regarding the ones available in-bulk and improper thermal treatment in the case of the canned ones. Moreover, the ability of both pathogens to survive for 5 days at 4 °C, in some products, has been exhibited.     

Changes on phenolic and carotenoid composition of high intensity pulsed electric field and thermally treated fruit juice–soymilk beverages during refrigerated storage

The effects of high intensity pulsed electric fields (HIPEF) (35 kV/cm with 4 μs bipolar pulses at 200 Hz for 800 or 1400 μs) or thermal (90 °C, 60 s) treatments over phenolic and carotenoid compounds of a fruit juice–soymilk (FJ–SM) beverage stored at 4 °C were evaluated and compared, having the untreated beverage as a reference. Coumaric acid, narirutin and hesperidin were the most abundant phenolic compounds in the FJ–SM beverage, while the main carotenoids were lutein, zeaxanthin and β-carotene. Immediately after HIPEF or heat processing, hesperidin content of the beverage showed a huge rise, resulting in a significant increase on the total phenolic concentration. Regarding carotenoid concentration, HIPEF or thermal treatment lead to a significant decrease; lutein, zeaxanthin and β-cryptoxanthin being the most affected compounds. In contrast, the content of some individual phenolics and carotenoids increased with time, while others tended to decrease or remained with no significant changes with regards to their initial values. Total phenolic concentration seemed to be highly stable during storage; while, total carotenoid content gradually diminished, irrespectively of the treatment applied. Overall, the changes observed in HIPEF treated FJ–SM beverage were less than those in the heat processed one. Hence, HIPEF is a feasible technology to obtain FJ–SM beverages with extended shelf-life and a similar profile of antioxidant compounds to freshly made beverages.     

The effect of high hydrostatic pressure on the microbiological quality and physical–chemical characteristics of Pumpkin (Cucurbita maxima Duch.) during refrigerated storage

Pumpkins were processed at high hydrostatic pressure (HHP) ranging from 350 to 550 MPa for 0.5 min to 30 min. Two different nonlinear mathematical models were compared to fit the inactivation kinetics. The second model consistently produced better fits to the inactivation data than the first model (Weibull model). According to the inactivation of microorganisms, pumpkin was subjected to 450 MPa/15 min and 550 MPa/10 min. The microbiological and physicochemical changes in pumpkin subjected to (HHP) and thermal-treated (854 °C/5 min) were compared during 4 °C storage. The total plate counts (TPC) treated with thermal processing, 450 MPa/15 min and 550 MPa/10 min were 5.12, 4.02 and 1.71 log₁₀ CFU/g, respectively on the 60th day. The growth of microorganisms caused the increase in ΔE, decrease in hardness in other treatments. Treatment of 550 MPa for 10 min had little effect on color during storage. There were no significant changes in the L^⁎, a^⁎ and b^⁎ values (p > 0.05). The hardness of pumpkin treated with 550 MPa/10 min decreased by 32.28% after 60 days. A greater retention of the original color, Vc and antioxidant capacity and increased total phenols were observed in 550 MPa/10 min-treated samples immediately after processing. During storage, color changed, Vc content, total phenols and the antioxidant activity were decreased. While the soluble solids content (SSC), sugars and pH value of pumpkin with HHP or thermal treatment did not show significant change immediately during 60-day storage. Based on these results, working at 550 MPa for 10 min ensures physicochemical and high standard of sanitation parameters in pumpkin.Industrial relevancePumpkin (Cucurbita maxima Duch.) is one of the popular vegetables, and fresh-cut pumpkin requires strict processing treatment and storage conditions to protect its quality. HHP is one promising novel non-thermal technique and is likely to replace thermal processes. A better knowledge of effects of storage temperature on the quality of HHP-treated pumpkin and its storage time prediction through microbiological quality and physical–chemical characteristics analysis of these changes is necessary. The available data would provide technical support for commercial application of the HHP technique in fresh-cut pumpkin processing.     

Determination of biogenic amines in fresh unpacked and vacuum-packed beef during storage at 4°C

Biogenic amines, putrescine, cadaverine, and histamine were determined in unpacked and vacuum-packed beef; during storage at 4°C for 12 and 35 days, respectively, under the same conditions. Analysis by High Performance Liquid Chromatography in both kind of samples, showed variation of cadaverine and histamine with an increasing tendency to a definite increase of putrescine. In unpacked samples, maximum mean contents for each amine reached 10.4, 5.2 μg/g for putrescine and cadaverine, respectively (12th day) and 2.2 μg/g for histamine (5th day). The total amine content reached 16.5 μg/g (12th day). After 8 days of storage, organoleptic fall-off began and, on the 12th day, all samples were disqualified. In vacuum packs, amine levels increased after 19 days. Maximum levels were determined for putrescine on the 35th day (36.3 μg/g), for cadaverine on the 26th day (28.9 μg/g) and for histamine on the 35th day (19.0 μg/g). Although the vacuum-packed beef was organoleptically acceptable up to 35 days, the total amine levels were greater than 5 μg/g after the 12th day, indicating a leveling off of quality.     

Changes in quality attributes of pulsed light and thermally treated mixed fruit beverages during refrigerated storage (4 °C) condition

The effect of batch pulsed light (PL) irradiation (3000 J cm⁻²) on the shelf-life of the beverage blend comprising apple ber (Indian jujube), carambola (star fruit), and black table grapes was investigated. The equivalent thermally treated beverage (90 °C|5 min) exhibited greater stability from microbial and enzymatic spoilage but retained 27% less antioxidants and 14% less vitamin C than PL-treated juice. Thermally and PL-treated blends possessed sensory scores of 5.8 and 7.2, respectively. The beverage's microbial shelf-life (population ≤ 6-log₁₀ cfu/mL) was extended to 45 days at 4 °C after the PL treatment. The PL exposure did not alter the pH and soluble solids during storage. The PL-treated juice, after 45 days, was placed on par with the freshly prepared juice by the sensory panel. The PL-treated juice preserved 61% more antioxidants, 38.8% more phenolics, and 68.2% more vitamin C than the thermally pasteurized beverage after 45 days of refrigerated storage.Industrial relevanceWhile the fruit processing industry demands microbial safety and enzymatic stability, today's consumer demands juices of high nutritional quality. This study utilizes under-explored fruits like apple ber (Indian jujube) and carambola (star fruit) to make a shelf-stable mixed fruit beverage. This study will help the industry understand the potential of PL treatment in accomplishing microbial safety, enzymatic stability, and nutritional quality, along with the utilization of under-explored fruits.     

Mechanical and physical properties of thermally modified Scots pine wood in high pressure reactor under saturated steam at 120, 150 and 180 °C

Scots pine sapwood and heartwood were thermally modified under saturated steam at 120, 150 and 180 °C in a high pressure reactor. Mechanical properties such as dynamic and static modulus of elasticity (MOE), static modulus of rupture (MOR), Brinell hardness and impact toughness were evaluated. The static MOE for sapwood did not decrease substantially (approximately 1 %), not even with a high mass loss of more than 12 %, when the wood was modified at 180 °C. Static MOE of the wood increased approximately 14 %, when modified at 150 °C. Surprisingly, MOR increased by 15 %, when modified at 150 °C with mass loss of 2.3 %. Whereas impact strength and hardness decreased somewhat, when modified at 180 °C. Moreover, high anti-swelling efficiency values were obtained (60 % for sapwood and 52 % for heartwood) when modified at 180 °C.     

Glucose,fructose and sucrose increase the solubility of protein–tannin complexes and at high concentration,glucose and sucrose interfere with bisulphite bleaching of wine pigments

Wines were modified with increasing sugar concentrations and decreasing tannin concentrations and analysed by a combination of protein precipitation and bisulphite bleaching. Increasing sugar concentration decreased the precipitation of tannin and protein-precipitable polymeric pigments (PPP). The use of a hydrogen bond disruptor (urea) to reduce protein–tannin and protein–pigment complex formation showed that the effect of sugar concentration occurred by increasing the solubility of the tannin–protein complex, not by interfering with protein–tannin complex formation. By increasing the solubility of pigment–protein complexes, non-protein-precipitable polymeric pigments (nPPP) appeared to increase. There was also an increase in total polymeric pigments at each tannin concentration with increasing glucose and sucrose concentration, indicating that sugar concentration might also affect bisulphite bleaching of wine pigments. While a significant effect of sugar concentration on tannin–protein complex solubility was observed, these effects were greatest at sugar concentrations far in excess of normal wine making conditions. Under normal wine making conditions, sugar concentration will have a negligible effect on protein-precipitable tannin, PPP and nPPP concentrations.     

Inactivation of Salmonella Typhimurium in fresh cherry tomatoes using combined treatment of UV–TiO2 photocatalysis and high hydrostatic pressure

Food Science and Biotechnology - The antibacterial efficacy of UV–TiO2 photocatalysis pre-washing in a water-assisted system (UVT, 4.5&nbsp;mW/cm2, 5–15&nbsp;min) and high...     

Functional stability of gelatin–lignosulphonate films and their feasibility to preserve sardine fillets during chilled storage in combination with high pressure treatment

The physico-chemical and functional stability of gelatin (G) and gelatin–lignosulphonate (GLS) films stored during 4 weeks at 21 °C, (i) in container or (ii) in contact with oil, was examined. Addition of lignosulphonate dramatically increased ABTS radical scavenging and ferric ion reducing capacities, which remained practically unaltered after the storage period. GLS films exhibited reduced elongation at break, irrespective of storage medium, and retained their water resistance. The feasibility of using GLS film to improve the quality of sardine fillets during chilled storage, alone or in combination with high pressure treatment (300 MPa/10 min/7 °C), was evaluated. The combined use of GLS film with high pressure reduced microbial growth, total volatile basic compounds (TVB) and thiobarbituric acid reactive substances (TBARS) during chilled storage. No noteworthy high pressure-induced colour changes were observed in the sardine muscle using this treatment alone, although an increase in yellowness due to the combined treatment was detected.Industrial RelevanceAddition of lignosulphonate dramatically increased antioxidant properties (ABTS radical scavenging and ferric ion reducing) of gelatin films, which remained practically unaltered during 4 weeks of storage at room temperature. Application of those films confers stability during storage of chilled sardine, especially in combination with high pressure treatment. These novel packaging was promising for fish preservation.     

Functional properties of raw and cooked pork patties with added irradiated, freeze-dried green tea leaf extract powder during storage at 4 °C

Functional and sensory properties of raw and cooked pork patties with added irradiated freeze-dried green tea leaf extract powder were studied. Components of green tea were extracted by 70% ethanol, and the extract was irradiated to obtain a bright color. The irradiated green tea extract was freeze-dried and the powdered sample (0.1%) was added to the pork patties (Trt C). Pork patties without any ingredient (Trt A) and with nonirradiated, freeze-dried green tea extract powder (Trt B) were also prepared for comparison. Lipid oxidation, radical scavenging effect, color, and sensory properties of pork patties with treatments were analyzed at 5-day intervals for 15 days with storage at 4?°C. The lipid oxidation had a lower (P<0.05) and radical scavenging effect was greater (P<0.05) in the raw and cooked pork patties with added Trt B and Trt C, than those of Trt A (control). The pork patties with Trt B and Trt C had a higher Hunter color a*-value and less cooking loss than that of Trt A. Sensory panelists preferred the odor of the raw pork patties and color of the cooked pork patties of Trt C (P<0.05). Generally, no significant difference between Trt B and Trt C was found. Therefore, irradiated, freeze-dried green tea extract powder can be used for producing functionally-improved meat products.     

Bacterial spore inactivation at 45-65 °C using high pressure processing: Study of Alicyclobacillus acidoterrestris in orange juice

High pressure processing (HPP) is a new non-thermal technology commercially used to pasteurize fruit juices and extend shelf-life, while preserving delicate aromas/flavours and bioactive constituents. Given the spoilage incidents and economic losses due to Alicyclobacillus acidoterrestris in the fruit juice industry, the use of high pressure (200 MPa – 600 MPa) in combination with mild temperature (45 °C–65 °C) for 1–15 min, to inactivate these spores in orange juice were investigated. As expected, the higher the temperature, pressure and time, the larger was the A. acidoterrestris inactivation. The survival curves were described by the first order Bigelow model. For 200 MPa, D_45 °C = 43.9 min, D_55 °C = 28.8 min, D_65 °C = 5.0 min and z-value = 21.3 °C. At 600 MPa, D_45 °C = 12.9 min, D_55 °C = 7.0 min, D_65 °C = 3.4 min and z-value = 34.4 °C. Spores were inactivated at 45 °C and 600 MPa, and at 65 °C only 200 MPa was needed to achieve reduction in spore numbers.     

Effects of high hydrostatic pressure on microstructure,physicochemical properties and in vitro digestibility of oat starch/β-glucan mixtures

Oats do not contain gluten protein, and oat dough structure is formed mainly through the hydrogen bonding of starch and β-glucan. As a non-thermal processing technology, high hydrostatic pressure (HHP) is mainly used to modify starch and protein in food processing. This study investigated the effects of HHP treatment on the morphological, structural, thermal, pasting and in vitro digestion properties of oat starch/β-glucan mixtures. Results showed that β-glucan interconnects with amylose through hydrogen bonding and has a protective effect on the crystalline region of oat starch. Effect of HHP treatment on the crystal structure of mixture system goes through crystal structure perfection stage, crystallisation disintegration and gelatinisation stage. After 300–400 MPa treatment, the changes in particle surface were not obvious, the phase transition temperature, the ΔH_gel and the PT of mixtures increased, while the particle size, viscosity and BD values decreased. After 500–600 MPa treatment, mixtures were completely gelatinised, most of the particles swelled and deformed, the particle size increased significantly. The principal component analysis results show that the complexes were distributed in the same region with similar properties after the 300–400 MPa and 500–600 MPa treatments, respectively.     

Changes in the bacterial communities of vacuum-packaged pork during chilled storage analyzed by PCR–DGGE

In this study, PCR-denaturing gradient gel electrophoresis (DGGE) was used to investigate the bacterial communities of vacuum-packaged pork during chilled storage. Eight kinds of lactic acid bacteria (LAB) were identified from the strains isolated from MRS plates by PCR–DGGE of the V3 region, and Lactobacillus sakei was the representative isolate at the end of the monitoring. By means of the direct meat analysis of PCR–DGGE, LAB increased gradually and Carnobacterium sp./Car. divergens, Lactobacillus sakei and Lactococcus sp./Lc. piscium, became the predominant bacteria at the end of the storage. The results of Lactobacillus-specific PCR and DGGE showed that different Lactobacillus populations were present at different storage periods and Lb. sakei became the predominant bacteria in the end. In conclusion, the PCR–DGGE technique as a culture-independent method is applicable to monitoring bacterial population dynamics in vacuum-packaged pork.     

Changes in the bacterial communities of vacuum-packaged pork during chilled storage analyzed by PCR–DGGE

In this study, PCR-denaturing gradient gel electrophoresis (DGGE) was used to investigate the bacterial communities of vacuum-packaged pork during chilled storage. Eight kinds of lactic acid bacteria (LAB) were identified from the strains isolated from MRS plates by PCR–DGGE of the V3 region, and Lactobacillus sakei was the representative isolate at the end of the monitoring. By means of the direct meat analysis of PCR–DGGE, LAB increased gradually and Carnobacterium sp./Car. divergens, Lactobacillus sakei and Lactococcus sp./Lc. piscium, became the predominant bacteria at the end of the storage. The results of Lactobacillus-specific PCR and DGGE showed that different Lactobacillus populations were present at different storage periods and Lb. sakei became the predominant bacteria in the end. In conclusion, the PCR–DGGE technique as a culture-independent method is applicable to monitoring bacterial population dynamics in vacuum-packaged pork.     

Quality changes and shelf life of imported vacuum-packaged beef chuck during storage at 0°C

The objective of this study was to investigate differences in adipose tissue fatty acid composition among stress genotypes as well as to determine relationships of those fatty acids with performance, carcass and meat quality traits. Haplotypic analysis of parents and offspring was employed to assign 48 pigs to three stress genotypes of swine. Individual fatty acid profiles were determined on subcutaneous backfat. Stress genotype had a significant effect on the proportions of C14:0 (P<0.05), C16:0 (P<0.10), C16:1 (P<0.05) and C18:0 (P<0.05) fatty acids. After adjusting for stress and gender, there was a negative correlation between backfat thickness and essential fatty acids (linoleic and linolenic) (P<0.001). In contrast, the correlation of loin muscle area with C18:2 (P<0.01) and C18:3 (P<0.001) was positive. The degree of fat firmness was negatively correlated to the proportion of total unsaturated fatty acids (P<0.01). No significant correlations were observed between fatty acid contents and lean meat quality traits.     

Effect of Eryngium caeruleum essential oil on microbial and sensory quality of minced fish and fate of Listeria monocytogenes during the storage at 4°C

The present study investigated in vitro antimicrobial activity of Eryngium caeruleum essential oil (EEO) against five foodborne pathogenic bacteria based on microdilution and disk diffusion methods. Moreover, its effects on specific spoilage microorganisms, inoculated Listeria monocytogenes, and its sensory changes in minced fish were evaluated during 12 days of storage at refrigeration temperature. The results showed that Staphylococcus aureus and Escherichia coli were the most sensitive and the most resistant bacteria with a minimum inhibitory concentration of 0.125 and 1 mg/ml, as well as inhibition zones of 15.66 and 11.66 mm, respectively. Regarding the antimicrobial effect of EEO on the microbial profile and inoculated L. monocytogenes, treating with 0.4% EEO caused a significant decrease in the studied microorganisms when compared to the control group (p < 0.05). In addition, considering the sensory evaluation, the best scores were observed for the samples treated with 0.2% and 0.4% EEO. However, none of the groups obtained acceptable scores until the final day of storage except for the color attribute. In general, sensory evaluation and its correlation with microbial counting indicated that the treatment with 0.4% EEO was able to preserve the microbial quality of the minced fish at refrigeration temperature without any undesirable sensory effects.